The present invention relates generally to indwelling catheters and electrode leads and more particularly to introducer systems for introducing catheters and electrode leads into a desired portion of a patient""s body.
Catheters and leads are typically placed in a desired location in a patient""s body, particularly within the patient""s vasculature, by means of introducer systems. These introducer systems typically include an elongated sheath which is inserted into the blood vessel or other portion of the patient""s body, through which sheath the catheter or lead is introduced. In those circumstances in which the lead or catheter is to remain in the patient""s body for a considerable period of time, it is desirable to be able to remove the introducer sheath without removing the lead or catheter.
One commonly employed mechanism for removing the introducer sheath from around the catheter or electrode lead is to provide the sheath with weakened zones on either side of the sheath, allowing it to be tom or split along weakened zones and removed from the catheter or lead. One introducer system employing this mechanism is illustrated in U.S. Pat. No. 5,409,469 issued to Schaerf, incorporated herein by reference in its entirety. Another commonly employed mechanism for removing the sheath from around the catheter or lead is to simply slit the sheath along its length as it is pulled proximally along the lead or catheter and out of the patient""s body. One such slitter is disclosed in U.S. Pat. No. 4,997,424 issued to Little, also incorporated herein by reference in its entirety.
In many circumstances, it is desirable that a hemostasis valve be provided at the proximal end of the introducer sheath, allowing the introducer to be sealed around the lead or catheter body. The presence of the hemostasis valve, which typically includes a rigid housing containing a compressible seal which engages the circumference of the lead body, poses a problem with regard to removal of the introducer sheath. One approach to this problem is to make the hemostasis valve splittable, along with sheath. An introducer system employing this mechanism is disclosed in U.S. Pat. No. 5,125,904 issued to Lee, also incorporated herein by reference in its entirety. An alternative solution to the problem of providing a hemostasis valve in the context of a splittable sheath is to simply make the hemostasis valve removable from the sheath, so that the sheath thereafter can be split. Introducer systems employing this mechanism are disclosed in U.S. Pat. No. 5,250,033, issued to Evans et al and U.S. Pat. No. 4,473,067 issued to Schiff, both of which are also incorporated herein by reference in their entireties. In the Evans et al patent, a threaded coupling, provided with a pre-weakened zone, engages a removable hemostasis valve. In Schiff, a splittable sheath is simply compressed around the end of a removable hemostasis valve. In both cases, the proximal end of the sheath is not configured to be connectable to standard luer type fittings.
The present invention provides an introducer system having a slittable sheath in conjunction with a removable hemostasis valve. Unlike similar systems described above, the present sheath is provided with a luer hub on its proximal end, allowing interconnection both to the removable hemostasis valve and to other devices such as valves, T-fittings and the like, using the luer hub. In conjunction with development of the invention, the inventors have determined that provision of a weakened zone, rendering the luer hub splittable, also renders it mechanically less reliable than would be desired. In order to provide a reliable mechanical and fluid connection to the hemostasis valve, the present inventors have designed a luer hub specifically adapted to be slit using a conventional catheter slitter. The improved luer hub comprises a relatively thin walled, generally conical or cylindrical member provided with one or more laterally extending tabs for engagement with the internal threading of a luer fitting, such as the luer fitting on the associated hemostasis valve. The tab or tabs may be molded as part of the slittable conical or cylindrical member or may be located on a rib or ribs extending longitudinally along the conical or cylindrical member. At least one portion of the conical or cylindrical member, hereafter referred to as the xe2x80x9cslittable portionxe2x80x9d is intended to be slit by means of a slitter, after removal of the associated hemostasis valve. The slitter also is employed to slit the introducer sheath, carrying the luer hub. The slittable portion of the conical or cylindrical member is located angularly displaced from the tab or tabs. The luer hub is preferably also provided with a handle, coupled to the conical member and angularly displaced from the portion of the conical or cylindrical member which is intended to be slit. The handle is preferably located diametrically opposite the slittable portion of the conical member, and if a longitudinally extending rib is provided it is longitudinally aligned with the rib.
In a preferred embodiment of the invention, the sheath is reinforced by means of one or more reinforcement fibers or bands, which are preferably arranged as a coil or braid, along the length of the sheath body. In construction, the sheath in these embodiments thus resembles a guiding catheter, and provides for a high degree of kink resistance along the length of the sheath when bent. The sheath may also optionally be provided with a slittable radiopaque marker located at the distal tip of the sheath.
In one embodiment of the invention, the introducer system is provided with a slitter particularly optimized for use in conjunction with a reinforced introducer sheath. The slitter is provided with a groove, formed in the slitter handle in which the lead or catheter body is located, protecting it from damage by the cut edges of the sheath, as the sheath is pulled proximally over the slitter.